dbcve.org
NbconvertApplication · Jupyter

CVE-2026-39377

MEDIUM · 6.5 CVSS v3.1 Published 2026-04-21
Fix available
A fix is available. Upgrade to 7.17.1 or later.
See remediation →
72/100
Remediation priority · Elevated
Remotely reachable No privileges

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
The nbconvert tool, jupyter nbconvert, converts Jupyter notebooks to various other formats via Jinja templates. Versions 6.5 through 7.17.0 allow arbitrary file writes to locations outside the intended output directory when processing notebooks containing crafted cell attachment filenames. The `ExtractAttachmentsPreprocessor` passes attachment filenames directly to the filesystem without sanitization, enabling path traversal attacks. This vulnerability provides complete control over both the destination path and file extension. Version 7.17.1 contains a patch.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

The nbconvert tool versions 6.5 through 7.17.0 contain a path traversal vulnerability in the ExtractAttachmentsPreprocessor. When processing notebooks with crafted cell attachment filenames, the preprocessor passes filenames directly to the filesystem without sanitization, allowing attackers to write arbitrary files to any location on the system where the nbconvert process has write permissions.

MitigationUpgrade nbconvert to version 7.17.1 or later. If immediate patching is not possible, restrict nbconvert execution to sandboxed environments with limited filesystem access and validate notebook contents before processing.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
NbconvertApplication
Affected:>= 6.5.0, < 7.17.1

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
Required
Scope
Unchanged
Confidentiality
None
Integrity
High
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Check nbconvert installation and version
    Run 'jupyter nbconvert --version' or 'pip show nbconvert' to retrieve the installed version
    Affected if Version is >= 6.5.0 and < 7.17.1
  2. Identify notebook processing workflows
    Review any scripts, pipelines, or automated systems that invoke nbconvert, particularly those processing notebooks from untrusted sources
    Affected if nbconvert processes notebooks with cell attachments
  3. Inspect ExtractAttachmentsPreprocessor usage
    Search conversion commands or configuration files for '--to markdown' or '--to html' with attachment-containing notebooks, as this triggers the vulnerable preprocessor
    Affected if ExtractAttachmentsPreprocessor is invoked during notebook conversion
  4. Audit filesystem write locations
    Identify directories where nbconvert output is written and verify permissions - the vulnerability allows files to be written outside the intended output directory
    Affected if Output directory permissions allow arbitrary file creation outside intended path

You are affected if nbconvert version is between 6.5.0 and 7.17.1 (inclusive) and you process notebooks containing cell attachments using ExtractAttachmentsPreprocessor functionality.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 7.17.1 or later
Fixed in 7.17.1
Interim mitigation

Upgrade nbconvert to version 7.17.1 or later. If immediate patching is not possible, restrict nbconvert execution to sandboxed environments with limited filesystem access and validate notebook contents before processing.

Recommended fix High confidence

nbconvert version 7.17.1 or later

  1. Check the current nbconvert version by running: pip show nbconvert or pip list | grep nbconvert
  2. Upgrade nbconvert to version 7.17.1 or later using: pip install --upgrade nbconvert>=7.17.1
  3. Verify the upgrade was successful by running: pip show nbconvert and confirming the version is 7.17.1 or higher
  4. Test that nbconvert still functions correctly with your notebooks

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Nbconvert Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing3.0 h
  • Review / QA2.0 h
11.0 hours of engineering $1,930
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,088.

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2026-39377 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

Get it on GitHub Scan in the browser

References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-39377 in production — separate from our analysis above.

No notes yet

Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.

What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data